Water level control method and device of steam generator and computer equipment

Abstract

The invention relates to a water level control method and device of a steam generator and computer equipment. The method comprises the steps that under the condition that it is detected that a main feed water valve of the steam generator has an upward floating fault, the feed water flow adjustment amount of the steam generator is determined according to the inlet and outlet water flow, the current water level value and the preset water level fixed value of the steam generator; determining an opening signal of a bypass valve based on a preset corresponding relation between the feed water flow and the opening signal of the bypass valve of the steam generator and the feed water flow adjustment amount; and the opening degree of the bypass valve is adjusted according to the opening degree signal, so that water level control over the steam generator is achieved. By the adoption of the method, disturbance to other steam generators can be avoided while the water level of the steam generator with the main water supply valve having the floating fault is adjusted to the stable state.

Description

Technical Field

[0001] The present application relates to the technical field of instrument control systems, and in particular to a water level control method, device, and computer equipment for a steam generator. Background Art

[0002] The steam generator water level control system is one of the most important and sensitive control systems in nuclear power plants. Its control stability is crucial for the safe and stable operation of nuclear power units. According to statistics, abnormal steam generator water level control is the main cause of unit transients or reactor automatic shutdowns.

[0003] Generally, the most common failure mode of a steam generator is a drift failure of the main feedwater valve. The so-called drift failure refers to a failure of the main feedwater valve, which causes the actual opening of the main feedwater valve to be greater than the required opening. Since the pressure difference between the feedwater main pipe and the steam main pipe of the steam generator (steam-water pressure difference) remains basically unchanged, the feedwater flow of the steam generator will increase, and the water level of the steam generator will continue to rise. In severe cases, it will trigger the automatic shutdown of the reactor of the nuclear power unit.

[0004] Currently, the aforementioned drift fault can be addressed by reducing the feedwater pump speed, thereby reducing the steam-water pressure differential and thereby reducing the feedwater flow rate to the steam generator. However, in this control approach, since multiple steam generators share the same feedwater pump in real-world scenarios, adjusting the feedwater pump speed will significantly disrupt other steam generators that are not experiencing the aforementioned drift fault. Summary of the Invention

[0005] Based on this, it is necessary to provide a steam generator position control method, device and computer equipment to address the above technical problems, which can adjust the water level of a steam generator with a main water supply valve floating fault to a stable state while avoiding causing disturbances to other steam generators.

[0006] In a first aspect, the present application provides a water level control method for a steam generator, comprising:

[0007] When a drift fault is detected in the main feedwater valve of the steam generator, the feedwater flow adjustment amount of the steam generator is determined according to the inlet and outlet water flow of the steam generator, the current water level value and the preset water level value;

[0008] Determining the bypass valve opening signal based on a preset correspondence between the feedwater flow rate and the bypass valve opening signal of the steam generator, and the feedwater flow rate adjustment amount;

[0009] The opening of the bypass valve is adjusted according to the opening signal to achieve water level control of the steam generator.

[0010] In one embodiment, the inlet and outlet water flows include at least feed water flow and steam flow; the feed water flow adjustment amount of the steam generator is determined based on the inlet and outlet water flows, the current water level value and the preset water level constant of the steam generator, including: determining a first feed water flow reduction amount based on the flow difference between the feed water flow and the steam flow; determining a height difference between the current water level value of the steam generator and the preset water level constant; determining a second feed water flow reduction amount based on the height difference and the shape of the steam generator; and determining the sum of the first feed water flow reduction amount and the second feed water flow reduction amount as the feed water flow adjustment amount of the steam generator.

[0011] In one embodiment, the inlet and outlet water flows also include sewage flow; based on the flow difference between the feed water flow and the steam flow, the first feed water flow reduction is determined, including: the flow difference between the feed water flow and the outlet water flow is determined as the first feed water flow reduction; wherein the outlet water flow includes steam flow and sewage flow.

[0012] In one embodiment, detecting that a main water supply valve of a steam generator has an upward drift fault includes: obtaining one or more sets of target parameters of the steam generator, and detecting whether each set of target parameters meets its own corresponding detection conditions; wherein the target parameters are parameters used to reflect the water level state of the steam generator; if the number of sets of target parameters that meet their own corresponding detection conditions is not less than a preset value, it is determined that a main water supply valve of the steam generator has been detected to have an upward drift fault.

[0013] In one embodiment, one or more sets of target parameters of the steam generator are obtained, and each set of target parameters is detected to see whether it meets its corresponding detection conditions, including at least one of the following items: the steam flow of the steam generator and the feed water flow detected by multiple flow detection devices installed on the steam generator are obtained as a set of target parameters, and the flow difference between each feed water flow and the steam flow is detected to see whether it is greater than a first threshold; if so, it is determined that the target parameters meet their corresponding detection conditions; the main feed water valve opening signal and the required opening signal of the main feed water valve corresponding to the secondary loop mirror load of the steam generator are obtained as a set of target parameters, and the opening difference between the main feed water valve opening and the required opening is detected to see whether it is greater than a second threshold; if so, it is determined that the target parameters meet their corresponding detection conditions; the current water level value and the preset water level setting value of the steam generator are obtained as a set of target parameters, and the height difference between the current water level value and the water level setting value is detected to see whether it is greater than a third threshold; if so, it is determined that the target parameters meet their corresponding detection conditions.

[0014] In one embodiment, the opening signal of the bypass valve is determined based on the corresponding relationship between the preset feed water flow and the opening of the bypass valve of the steam generator, and the feed water flow adjustment amount, including: when the feed water flow adjustment amount does not exceed the preset adjustment amount, the opening signal of the bypass valve is determined based on the corresponding relationship between the preset feed water flow and the opening of the bypass valve of the steam generator, and the feed water flow adjustment amount; wherein the preset adjustment amount is used to characterize the change in feed water flow caused by the bypass valve switching from a fully open state to a fully closed state.

[0015] In one embodiment, after adjusting the opening of the bypass valve according to the opening signal, the method further includes: determining whether the water level value of the steam generator has recovered to the water level set value at preset time intervals; if not, returning to the step of determining the feed water flow adjustment amount of the steam generator based on the inlet and outlet water flow of the steam generator, the current water level value and the preset water level set value until the water level value of the steam generator recovers to the water level set value.

[0016] In one embodiment, based on the correspondence between a preset feed water flow and an opening signal of a bypass valve of a steam generator, and a feed water flow adjustment amount, the opening signal of the bypass valve is determined, including: determining a target difference between the feed water flow of the steam generator and the feed water flow adjustment amount when the bypass valve is in a fully open state; and in the correspondence between the preset feed water flow and the opening signal of the bypass valve of the steam generator, determining the opening signal of the bypass valve corresponding to the target difference.

[0017] In a second aspect, the present application further provides a water level control device for a steam generator, comprising:

[0018] An adjustment amount determination module is used to determine the feedwater flow adjustment amount of the steam generator based on the inlet and outlet water flow of the steam generator, the current water level value and the preset water level value when a drift fault is detected in the main feedwater valve of the steam generator;

[0019] an opening signal determination module, configured to determine the opening signal of the bypass valve based on a correspondence between a preset feedwater flow rate and the opening signal of the bypass valve of the steam generator, and a feedwater flow rate adjustment amount;

[0020] The bypass valve adjustment module is used to adjust the opening of the bypass valve according to the opening signal to achieve water level control of the steam generator.

[0021] On the third aspect, the present application also provides a computer device, including a memory and a processor, the memory storing a computer program, and the processor implementing the following steps when executing the computer program: when a drift fault is detected in the main feed water valve of the steam generator, determining the feed water flow adjustment amount of the steam generator according to the inlet and outlet water flow of the steam generator, the current water level value and the preset water level constant; determining the opening signal of the bypass valve based on the correspondence between the preset feed water flow and the opening signal of the bypass valve of the steam generator, and the feed water flow adjustment amount; adjusting the opening of the bypass valve according to the opening signal to achieve water level control of the steam generator.

[0022] Fourthly, the present application also provides a computer-readable storage medium having a computer program stored thereon, which implements the following steps when the computer program is executed by a processor: when a drift fault is detected in the main feed water valve of the steam generator, determining the feed water flow adjustment amount of the steam generator according to the inlet and outlet water flow of the steam generator, the current water level value and the preset water level constant; determining the opening signal of the bypass valve based on the correspondence between the preset feed water flow and the opening signal of the bypass valve of the steam generator, as well as the feed water flow adjustment amount; adjusting the opening of the bypass valve according to the opening signal to achieve water level control of the steam generator.

[0023] In a fifth aspect, the present application also provides a computer program product, comprising a computer program, which implements the following steps when executed by a processor: when a drift fault is detected in the main feed water valve of the steam generator, determining the feed water flow adjustment amount of the steam generator according to the inlet and outlet water flow of the steam generator, the current water level value and the preset water level constant; determining the opening signal of the bypass valve based on the correspondence between the preset feed water flow and the opening signal of the bypass valve of the steam generator, and the feed water flow adjustment amount; adjusting the opening of the bypass valve according to the opening signal to achieve water level control of the steam generator.

[0024] The above-mentioned steam generator water control method, device, and computer equipment, when detecting a drift fault in the main feedwater valve of the steam generator, determine the steam generator feedwater flow adjustment amount based on the steam generator's inlet and outlet water flow, the current water level value, and a preset water level setting value, and determine the bypass valve opening signal based on the correspondence between the preset feedwater flow and the steam generator's bypass valve opening signal and the feedwater flow adjustment amount, and then adjust the bypass valve opening according to the opening signal to achieve water level control of the steam generator. The above-mentioned scheme, when the main feedwater valve of the steam generator has a drift fault, controls the water level of the steam generator by adjusting the bypass valve opening. On the one hand, it can quickly control the steam generator water level to the preset water level setting value, avoiding triggering the unit's reactor automatic shutdown; on the other hand, each steam generator has an independent bypass valve. Therefore, controlling the water level of the steam generator by adjusting the bypass valve opening can also prevent disturbances to other steam generators that share the same feedwater pump and whose main feedwater valves do not have the drift fault. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the following briefly introduces the drawings required for use in the embodiments of the present application or related technical descriptions. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 This is the steam generator water level control logic diagram;

[0027] Figure 2 A schematic flow chart of a water level control method for a steam generator provided in one embodiment;

[0028] Figure 3 is the bypass valve opening characteristic curve of the steam generator;

[0029] Figure 4 This is a schematic diagram of the process quantity response characteristics when simulating a 5% drift fault in the main feedwater valve under full-power operation of a nuclear power unit.

[0030] Figure 5 This is a schematic diagram of the process quantity response characteristics when simulating a 10% drift fault in the main feedwater valve under full-power operation of a nuclear power unit.

[0031] Figure 6 A schematic diagram of a flow chart for determining a feedwater flow adjustment amount of a steam generator provided in one embodiment;

[0032] Figure 71 is a schematic diagram of the appearance of a steam generator;

[0033] Figure 8 It is a schematic diagram of the correction coefficient corresponding to the feed water temperature;

[0034] Figure 9 A schematic diagram of a flow chart for determining that a main feedwater valve of a steam generator has an upper drift fault is provided in one embodiment;

[0035] Figure 10 1. A logic diagram of a method for automatically controlling a bypass valve in a main feedwater valve drift fault mode of a steam generator in one embodiment;

[0036] Figure 11 for Figure 10 Logic diagram for judging the drift fault of the middle main water supply valve;

[0037] Figure 12 for Figure 10 Logic diagram for automatic setting of the bypass valve;

[0038] Figure 13 is a flow chart of a water level control method for a steam generator in another embodiment;

[0039] Figure 14 This is a structural block diagram of a water level control device for a steam generator provided in one embodiment;

[0040] Figure 15 The figure is a diagram of the internal structure of a computer device provided in one embodiment. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0042] Before describing the water level control method, device, and computer equipment for a steam generator provided in the present application, a brief introduction to the relevant contents of the steam generator is first given.

[0043] A steam generator is a vertical, natural circulation device that produces saturated steam. Reactor coolant flows within the heat transfer tubes, transferring heat to the secondary water circuit outside the tubes. This secondary water circulates naturally within the steam generator, and as it flows through the heat transfer tubes, some of the water becomes saturated steam, which is supplied to the main steam turbine and auxiliary equipment, thereby driving the turbine to generate electricity. The purpose of a steam generator water level control system is to maintain the water level on the secondary side of the steam generator at the required set value (referred to as the set water level or fixed water level).

[0044] The water level control of the steam generator mainly includes the main feed water pump speed control and the main feed water valve opening control. Among them, the main feed water pump speed control is mainly used to adjust the pressure difference ΔPSW (steam-water pressure difference) between the feed water main pipe and the steam main pipe while maintaining the constant pressure drop of the regulating valve, so that it changes parabolically with the load change, and the actuator of the main feed water pump speed control is the main feed water pump. The main purpose of the main feed water valve opening control is to set up an independent water level regulation system for each steam generator, and to change the feed water flow by changing the opening of the main feed water valve to control the steam generator water level L SG The purpose is to control the opening of the main water supply valve, and the actuators for controlling the opening of the main water supply valve are the main water supply valve (referred to as the main valve) and the bypass water supply valve (referred to as the bypass valve).

[0045] The steam generator water level control system is mainly composed of steam generator, main feed water pump, main feed water valve and corresponding pipelines. The steam generator water level control logic diagram is as follows: Figure 1 shown.

[0046] Where ΔP SW is the pressure difference between steam and water, Q ST is the steam flow rate, p ST is the steam pressure, Q FW is the water flow rate, L SG is the steam generator water level (current water level value), L SP The water level setting value of the steam generator (preset water level setting value), P PW For the second circuit mirror load wide range, T FW is the feed water temperature, P PN For the narrow range of the secondary circuit mirror load, V O1 Main water supply valve opening signal (main water supply valve demand opening signal), V O1 is the bypass valve opening signal, R PO is the speed of the water pump. T1, T6, T7, T8 are the filtering time, T2, T9, T 10 is the integration time, T3, T4, T5, T 11 is the lag time, T d1 is the differential time, K p1 , K p2 , K p3 Regulator gain coefficient, K1, K2, K3, K4 are the gain coefficients of the subsequent links, K p4 is the P regulator gain coefficient.

[0047] Steam flow (volume flow) Q ST At the steam pressure P ST The corrected mass flow is generated and then compared with the water flow Q through the filter module. FWThe difference is made to generate the steam-water deviation signal. The steam-water deviation signal is input to the flow regulator (PI) together with the water level regulator output signal to control the opening signal of the main water supply valve. PN Together with the output signal of the water level regulator, it is input to the P regulator to control the opening signal of the bypass valve. Steam flow (volume flow) Q ST The speed constant is generated by the filter module and the steam-water pressure difference ΔP SW The difference is input to the PI regulator to control the speed of the three main feedwater pumps. The two main feedwater pumps have a certain lag in the regulation process, so a first-order inertia link is used to characterize them.

[0048] Typically, the most common failure mode for steam generators is a main feedwater valve drift failure. Currently, when a main feedwater valve drift failure occurs, the steam generator water level is controlled by reducing the feedwater pump speed. Because multiple steam generators share the same feedwater pump, this can cause significant disturbances to other steam generators that are not experiencing this drift failure.

[0049] Based on this, in an exemplary embodiment, as Figure 2 As shown, a method for controlling the water level of a steam generator is provided, which can be applied to a computer device. The computer device can be a backend server corresponding to the steam generator, or a control terminal corresponding to the steam generator. In this embodiment, the method includes the following steps:

[0050] S201, when it is detected that a main feedwater valve of a steam generator has an upward drift fault, determining a feedwater flow adjustment amount of the steam generator according to the inlet and outlet water flows of the steam generator, the current water level value and a preset water level value.

[0051] As previously mentioned, during the operation of a steam generator, as the secondary circuit water in the steam generator flows through the heat transfer tubes, some of the water becomes saturated steam and flows out of the steam generator, reducing the amount of water in the steam generator and, in turn, lowering the water level on the secondary side of the steam generator (referred to as the steam generator water level). Simultaneously, because the steam generator's feedwater valve (main valve and / or bypass valve) and feedwater pump deliver external water to the steam generator, the amount of water in the steam generator increases, thereby raising the water level on the secondary side of the steam generator.

[0052] To ensure the safe operation of nuclear power units, the water level in the steam generator must be maintained at a set value. That is, under normal operating conditions, the water level in the steam generator must remain stable. Therefore, during the steam generator's operation, the steam flow rate of saturated steam flowing out of the steam generator and the feedwater flow rate of water flowing into the steam generator must be equal. The steam flow rate reflects the amount of water flowing out of the steam generator, while the feedwater flow rate reflects the amount of water flowing into the steam generator. The steam generator's inlet and outlet water flow rates include at least the feedwater flow rate and the steam flow rate.

[0053] If a steam generator's main feedwater valve experiences an over-floating fault, the steam generator's feedwater flow rate will increase, causing the steam generator's water level to continue to rise, causing the current steam generator water level to exceed the aforementioned set water level. To prevent the steam generator water level from continuing to rise and triggering an automatic reactor shutdown, the steam generator's feedwater flow rate needs to be adjusted to reduce the amount of water in the steam generator, lowering the current steam generator water level and restoring the steam generator water level to the aforementioned set water level.

[0054] It is understandable that when a drift fault is detected in the main feedwater valve of the steam generator, the current water level of the steam generator is already higher than the above-mentioned water level setting, while external water still flows into the steam generator at the current feedwater flow rate. Therefore, when a drift fault is detected in the main feedwater valve of the steam generator, the factors affecting the feedwater flow rate that needs to be adjusted for the steam generator include two aspects: one is the feedwater flow rate caused by the current water level of the steam generator being higher than the water level setting, and the other is the feedwater flow rate caused by the difference between the feedwater flow rate of the steam generator and the steam flow rate.

[0055] Based on this, if a steam generator's main feedwater valve is detected to have an over-floating fault, the steam generator's inlet and outlet water flow rates, such as the steam generator's feedwater flow rate and steam flow rate, can be obtained as detected by various flow detection devices installed on the steam generator. For example, the steam generator may be redundantly equipped with flow detection devices for detecting the feedwater flow rate. Therefore, the feedwater flow rates detected by multiple flow detection devices can be obtained. The average of the multiple feedwater flow rates detected can then be calculated as the steam generator's feedwater flow rate. Furthermore, the steam generator's preset water level setting and the steam generator's current water level value, as detected by a height detection device installed on the steam generator, can also be obtained. Thus, after obtaining the aforementioned inlet and outlet water flow rates, current water level value, and water level setting, the steam generator's feedwater flow rate adjustment amount can be determined based on the steam generator's inlet and outlet water flow rates, current water level value, and water level setting. The feedwater flow rate adjustment amount refers to the steam generator's feedwater flow rate adjustment required to restore the steam generator's water level value to the preset water level setting when the steam generator's main feedwater valve has an over-floating fault.

[0056] S202: Determine the opening signal of the bypass valve based on the corresponding relationship between the preset feedwater flow rate and the opening signal of the bypass valve of the steam generator, as well as the feedwater flow rate adjustment amount.

[0057] Typically, as the opening of the bypass valve changes, the amount of water flowing through the bypass valve into the steam generator will change accordingly. At the same time, the feed water flow of the steam generator will also change accordingly. Therefore, the correspondence between the feed water flow and the opening signal of the bypass valve of the steam generator can be pre-set.

[0058] For example, Figure 3 The figure shows the bypass valve opening characteristic curve for a steam generator. The horizontal axis of the coordinate system represents the bypass valve opening, and the vertical axis represents the feedwater flow rate. This characteristic curve represents the corresponding relationship between the feedwater flow rate and the bypass valve opening signal of the steam generator. The bypass valve opening signal refers to the degree of opening of the bypass valve compared to the opening ratio when the bypass valve is fully open. For example, when the bypass valve is fully open, the bypass valve opening signal is 100%; when the bypass valve is fully closed, the bypass valve opening signal is 0%, indicating that the bypass valve is fully closed; and when the bypass valve is half open, the bypass valve opening signal is 50%.

[0059] In the event that the main water supply valve has an over-floating fault, it is necessary to control the water level of the steam generator by adjusting the opening of the bypass valve. The water supply flow adjustment amount determined above is the water supply flow of the steam generator that needs to be adjusted. Based on the above-mentioned water supply flow adjustment amount, the water supply flow required to reduce the above-mentioned water supply flow adjustment amount and restore the water level value of the steam generator to the preset water level set value can be determined. Furthermore, the opening signal of the bypass valve corresponding to the above-mentioned required water supply flow can be determined in the corresponding relationship between the above-mentioned preset water supply flow and the opening signal of the bypass valve of the steam generator.

[0060] S203, adjusting the opening of the bypass valve according to the opening signal to achieve water level control of the steam generator.

[0061] After determining the bypass valve opening signal, the bypass valve opening can be adjusted based on the opening signal, for example, by adjusting the bypass valve opening to the opening indicated by the opening signal. Thus, by adjusting the bypass valve opening, the feedwater flow rate to the steam generator can be reduced, thereby lowering the current water level of the steam generator so that it gradually approaches the preset water level setting, thereby restoring the current water level of the steam generator to the preset water level setting, thereby achieving water level control of the steam generator.

[0062] Among them, the current water level value of the steam generator is restored to the preset water level value, which means that the height difference between the current water level value of the steam generator and the preset water level value is less than a preset threshold, and the preset threshold is not greater than the subsequent third threshold.

[0063] For example, Figure 4-Figure 5 The following are schematic diagrams of the process quantity response characteristics of the main feedwater valve with 5% and 10% drift faults under the full power operation condition of the simulated nuclear power unit. Figure 4-Figure 5 It can be determined that when the main water supply valve has an upward drift fault, the actual opening of the main water supply valve is larger than the required opening, and the steam-water pressure difference ΔP SW Basically remains unchanged, resulting in water flow Q FW The steam generator water level L SG Continuously rising, the steam generator water level L SG and steam generator water level set value L SP The deviation gradually expands. The main water supply valve opening demand signal V O1 Under the integral action of the regulating system, the valve is continuously closed and reaches the minimum opening of 0%. At the same time, the opening signal V O2The main feedwater valve continues to close due to water level deviation. Since the actual opening of the main feedwater valve has not changed, without intervention, the steam generator water level reactor protection logic will be directly triggered. A 10% overshoot of the main feedwater valve is very close to the steam generator water level high reactor automatic shutdown threshold.

[0064] As one of the most critical and sensitive control systems in a nuclear power plant, the steam generator water level control system (SGWL) ensures stable control, ensuring safe and stable operation of nuclear power units. Statistics show that abnormal SGWL control is the leading cause of transients or reactor shutdowns. Existing SGWL control systems feature redundant front-end sensors and intermediate controllers, significantly improving the reliability of both front-end and intermediate links. However, the non-redundant actuators in the SGWL remain a weak link. Abnormal operation of these actuators often leads to disturbances or transients in the SGWL control system. The actuator in the SGWL control system is the main feedwater valve, which is typically a pneumatically operated control valve. The most common failure mode is an abnormally high main feedwater level (high-level failure). Nuclear power plants have repeatedly experienced SGWL control failures due to malfunctions in the SGWL valve, the actuator in the SGWL control system, leading to serious reactor shutdowns. The operator response time after a main feedwater valve failure is very limited; in most cases, the time span from failure occurrence to automatic reactor shutdown is ≤10 minutes. Therefore, research on automatic bypass valve control methods for nuclear power plant steam generator water levels in the event of a main feedwater valve drift failure is of great engineering significance, helping to ensure the safe and stable operation of nuclear power units.

[0065] In the above-mentioned steam generator water level control method, when a main feedwater valve of a steam generator is detected to have an over-floating fault, the feedwater flow adjustment amount of the steam generator is determined based on the steam generator's inlet and outlet water flow, the current water level value, and a preset water level set value. The bypass valve opening signal is determined based on the correspondence between the preset feedwater flow and the steam generator's bypass valve opening signal, as well as the feedwater flow adjustment amount. The bypass valve opening signal is then adjusted according to the opening signal to achieve water level control of the steam generator. In the above-mentioned scheme, when a main feedwater valve of a steam generator has an over-floating fault, the water level of the steam generator is controlled by adjusting the bypass valve opening. On the one hand, the water level of the steam generator can be quickly controlled to the preset water level set value to avoid triggering an automatic shutdown of the unit's reactor. On the other hand, each steam generator has an independent bypass valve. Therefore, the water level control of the steam generator by adjusting the bypass valve opening can also prevent disturbances to other steam generators that share the same feedwater pump and whose main feedwater valves do not have an over-floating fault.

[0066] Based on the above embodiment, in an exemplary embodiment, the process of determining the opening signal of the bypass valve in S202 is further refined. Optionally, the following steps may be included:

[0067] Step 1: Determine a target difference between the feed water flow rate of the steam generator and the feed water flow rate adjustment amount when the bypass valve is in a fully open state.

[0068] In this embodiment, since the feedwater flow adjustment amount refers to the feedwater flow of the steam generator that needs to be adjusted in order to restore the water level value of the steam generator to a preset water level setting value when the main feedwater valve of the steam generator has an over-floating fault, rather than the feedwater flow used to restore the water level value of the steam generator to a preset water level setting value when the main feedwater valve of the steam generator has an over-floating fault, it is necessary to determine the feedwater flow used when adjusting the bypass valve opening to restore the water level value of the steam generator to the preset water level setting value based on the feedwater flow adjustment amount. In this way, after determining the feedwater flow adjustment amount, the target difference between the feedwater flow of the steam generator when the bypass valve is in the fully open state and the feedwater flow adjustment amount can be determined. The target difference can be understood as the feedwater flow used when adjusting the bypass valve opening to restore the water level value of the steam generator to the preset water level setting value.

[0069] Step 2: Determine the bypass valve opening signal corresponding to the target difference in the correspondence between the preset feed water flow rate and the bypass valve opening signal of the steam generator.

[0070] Furthermore, after the target difference is determined, the bypass valve opening signal corresponding to the target difference can be determined in the correspondence between the preset feed water flow rate and the bypass valve opening signal of the steam generator.

[0071] For example, Figure 3 As shown in the figure, the ordinate of the upper right vertex of the bypass valve opening characteristic curve of the steam generator is the feed water flow of the steam generator when the bypass valve is fully open, ΔQ FW is the feed water flow adjustment amount, then on the bypass valve opening characteristic curve, the ordinate is the ordinate of the upper right vertex and ΔQ FW The horizontal coordinate V of the target difference point O2 , which is the final opening signal of the bypass valve.

[0072] In this embodiment, the correspondence between the preset feed water flow and the opening signal of the bypass valve of the steam generator and the feed water flow adjustment amount can be used to quickly determine the opening signal of the bypass valve, thereby simplifying the process of determining the opening signal of the bypass valve and improving the water level control efficiency of the steam generator when the main feed water valve of the steam generator has an upward drift fault.

[0073] For example, based on the above embodiment, after adjusting the bypass valve opening according to the determined bypass valve opening signal, the steam generator feedwater flow rate is adjusted to the feedwater flow rate indicated by the bypass valve opening signal. Furthermore, as time progresses, the current water level of the steam generator changes. Therefore, the steam generator feedwater flow rate adjustment amount also changes over time, and thus, the required bypass valve opening signal also changes over time. Based on this, the steam generator water level can be controlled by periodically adjusting the bypass valve opening signal.

[0074] In an exemplary embodiment, after adjusting the opening of the bypass valve according to the opening signal in the above S203, the method may further include, at preset time intervals, determining whether the water level value of the steam generator has recovered to a preset water level set value; if not, returning to execute the above S201, and determining the feed water flow adjustment amount of the steam generator according to the inlet and outlet water flow of the steam generator, the current water level value and the preset water level set value, until the water level value of the steam generator recovers to the water level set value.

[0075] In this embodiment, after the bypass valve opening signal is initially determined and the opening of the bypass valve is adjusted according to the opening signal, it is possible to determine whether the water level value of the steam generator has recovered to the preset water level value at preset time intervals.

[0076] If not, it means that the problem of the current water level of the steam generator being higher than the preset water level setting value due to the main feedwater valve drift fault has not been solved at this time. Therefore, it is necessary to continue to control the water level of the steam generator by adjusting the bypass valve opening. Considering that the required bypass valve opening signal will change at this time, it is possible to return to the above-mentioned step of determining the feedwater flow adjustment amount of the steam generator based on the steam generator's inlet and outlet water flow, the current water level value, and the preset water level setting value to re-determine the new opening signal of the bypass valve. Then, the bypass valve opening is adjusted according to the new opening signal of the bypass valve until the water level of the steam generator returns to the preset water level setting value. In other words, when it is determined that the water level of the steam generator has returned to the preset water level setting value, the bypass valve opening adjustment can be stopped. At this point, the water level control of the steam generator is completed when the main feedwater valve of the steam generator has a drift fault.

[0077] In this embodiment, when there is an over-drift fault in the main water supply valve of the steam generator, the difference between the current water level value of the steam generator and the preset water level setting value can be periodically detected. Thus, the opening signal of the bypass valve can be adjusted according to the current water level control situation of the steam generator. This can make the opening adjustment of the bypass valve more in line with the current water level control situation of the steam generator, which is beneficial to the control accuracy and control efficiency of the water level control of the steam generator.

[0078] Considering that the bypass valve opening is limited, the feedwater flow rate adjustment amount that can be adjusted by adjusting the bypass valve opening is also limited. Therefore, in the case of a steam generator main feedwater valve having an over-floating fault, when the feedwater flow rate adjustment amount is too large, the steam generator water level value cannot be restored to the preset water level setting value by simply adjusting the bypass valve opening. Based on this, in order to restore the steam generator water level value to the preset water level setting value by simply adjusting the bypass valve opening to achieve steam generator water level control, after determining the feedwater flow rate adjustment amount, it is possible to first determine whether the feedwater flow rate adjustment amount exceeds the adjustment amount that can be adjusted by adjusting the bypass valve opening.

[0079] Based on this, in an exemplary embodiment, in the above S202, the bypass valve opening signal is determined based on the preset correspondence between the feedwater flow rate and the opening of the bypass valve of the steam generator, as well as the feedwater flow rate adjustment amount. If the feedwater flow rate adjustment amount does not exceed the preset adjustment amount, the bypass valve opening signal is determined based on the preset correspondence between the feedwater flow rate and the opening of the bypass valve of the steam generator, as well as the feedwater flow rate adjustment amount. The preset adjustment amount is used to represent the change in feedwater flow rate caused by the bypass valve switching from a fully open state to a fully closed state.

[0080] In this embodiment, the change in the steam generator feedwater flow rate caused by switching the bypass valve from fully open to fully closed can be measured and used as a preset adjustment amount. Furthermore, in order to restore the steam generator water level to the preset water level value simply by adjusting the bypass valve opening, the feedwater flow rate adjustment amount cannot exceed the preset adjustment amount.

[0081] Based on this, when the feed water flow adjustment amount does not exceed the preset adjustment amount, the bypass valve opening signal can be further determined based on the correspondence between the preset feed water flow and the opening of the bypass valve of the steam generator, as well as the feed water flow adjustment amount.

[0082] Thus, in the event of a drift fault in the main feedwater valve of the steam generator, whether to control the water level of the steam generator by adjusting the bypass valve is determined by a logical judgment based on the numerical relationship between the feedwater flow adjustment amount and the preset adjustment amount. If the feedwater flow adjustment amount does not exceed the preset adjustment amount, the water level of the steam generator is controlled by adjusting the bypass valve. If the water level of the steam generator has not recovered to the preset water level setting value, the bypass valve opening is adjusted according to the determined bypass valve opening signal. After the water level of the steam generator has recovered to the preset water level setting value, the bypass valve returns to an automatic control state, and can automatically adjust its opening according to the inlet and outlet water flow of the steam generator. In summary, in this embodiment, when a main feedwater valve of a steam generator has an over-floating fault, the water level of the steam generator can be controlled by adjusting the opening of the bypass valve only, so that the water level of the steam generator can be quickly controlled to a preset water level value, thereby avoiding triggering an automatic shutdown of the reactor of the unit, and preventing disturbances to other steam generators that share the same feedwater pump and whose main feedwater valves do not have an over-floating fault.

[0083] In an exemplary embodiment, Figure 6 As shown, based on the above-mentioned steam generator inlet and outlet water flow including at least feed water flow and steam flow, the process of determining the feed water flow adjustment amount of the steam generator in the above-mentioned S201 is further refined. Optionally, the following steps may be included:

[0084] S601: Determine a first feedwater flow reduction amount based on a flow difference between a feedwater flow and a steam flow.

[0085] In this embodiment, the inlet and outlet water flow of the above-mentioned steam generator includes at least feed water flow and steam flow, and the above-mentioned feed water flow can reflect the amount of water entering the steam generator, and the steam flow can reflect the amount of water leaving the steam generator. Therefore, the flow difference between the feed water flow and the steam flow can reflect the feed water flow that needs to be adjusted for the steam generator, and thus, the first feed water flow reduction can be determined based on the flow difference between the feed water flow and the steam flow.

[0086] S602, determining the height difference between the current water level value of the steam generator and a preset water level value.

[0087] When the main feedwater valve of the steam generator has an upward drift fault, the current water level value of the steam generator will be higher than the preset water level value. Therefore, the height difference between the current water level value of the steam generator and the preset water level value can be determined.

[0088] S603: Determine a second feedwater flow reduction amount based on the height difference and the shape of the steam generator.

[0089] After determining the height difference, a second feedwater flow reduction can be determined based on the height difference and the shape of the steam generator. The volume of water that needs to be reduced due to the increased water level in the steam generator (referred to as the feedwater volume) can be determined based on the height difference and the shape of the steam generator. Furthermore, the feedwater volume can be converted into a feedwater flow to obtain the second feedwater flow reduction.

[0090] Optional, such as Figure 7 As shown in FIG. 1 , a schematic diagram of the appearance of a steam generator is shown, wherein the shape of the steam generator is approximately cylindrical, and the cross-section of the steam generator is approximately circular. The feed water volume can be determined based on the height difference and the shape of the steam generator by first using the following formula (1).

[0091] V d =πr 2 (L SG -L SP ) (1)

[0092] Among them, V d is the feed water volume, r is the cross-sectional radius of the steam generator, L SG is the current water level value, L SP The preset water level value.

[0093] Afterwards, when converting the above feed water volume into feed water flow, it is necessary to consider the correction coefficient of water temperature to volume and the desired steam generator water level adjustment time, that is, how long it is expected to take to restore the steam generator water level value to the above preset water level value. Figure 8 The figure shows a schematic diagram of the correction coefficient corresponding to the feedwater temperature. The horizontal axis of the coordinate system is the feedwater temperature, i.e., the water temperature in the steam generator, and the vertical axis is the correction coefficient. Furthermore, the feedwater volume can be converted to the feedwater flow rate using the following formula (2) to obtain the second feedwater flow rate reduction.

[0094] ΔQ FW2 =V d / (K1T1) (2)

[0095] Where ΔQ FW2 is the reduction of the second feed water flow rate, K1 is the correction coefficient of the water temperature to the volume of the steam generator, and T1 is the water level adjustment time of the steam generator.

[0096] S604: Determine the sum of the first feedwater flow reduction amount and the second feedwater flow reduction amount as the feedwater flow adjustment amount of the steam generator.

[0097] As mentioned above, the factors that affect the feedwater flow rate that needs to be adjusted for the steam generator include two aspects. One aspect is the feedwater flow rate caused by the current water level value of the steam generator being higher than the water level set value, and the other aspect is the feedwater flow rate caused by the difference between the feedwater flow rate of the steam generator and the steam flow rate. The feedwater flow rate caused by the difference between the feedwater flow rate of the steam generator and the steam flow rate is the above-mentioned first feedwater flow reduction, and the feedwater flow rate caused by the current water level value of the steam generator being higher than the water level set value is the above-mentioned second feedwater flow reduction. Therefore, the sum of the above-mentioned first feedwater flow reduction and the above-mentioned second feedwater flow reduction can be determined as the feedwater flow adjustment amount of the steam generator. For example, as shown in the following formula (3):

[0098] ΔQ FW =ΔQ FW1 +ΔQ FW2 (3)

[0099] Where ΔQ FW is the water flow adjustment, ΔQ FW1 is the first water flow reduction, ΔQ FW2 is the reduction of the second water supply flow rate.

[0100] In this embodiment, the feed water flow adjustment amount of the steam generator is determined by the feed water volume and the flow difference between the inlet and outlet water flows of the steam generator, wherein the above ΔQ FW1 The calculation process can be called steam generator quality deviation calculation, ΔQ FW2 The calculation process can be called steam generator feed water demand calculation. According to the steam generator quality deviation calculation and the steam generator feed water demand calculation, the feed water flow adjustment amount is obtained, which has the characteristics of high accuracy and can improve the water level control effect of the steam generator.

[0101] In order to ensure the water quality of the steam generator and to ensure the normal use of the steam generator, the steam generator is usually provided with a sewage system to discharge the water in the steam generator and generate sewage that needs to flow out of the steam generator. The flow rate of the above sewage is used as the sewage flow rate, which can reflect the water discharge amount of the steam generator together with the above steam flow rate.

[0102] Based on this, in an exemplary embodiment, to more accurately determine the feedwater flow adjustment amount, the process of determining the first feedwater flow reduction amount in S601 is further refined, based on the steam generator's inlet and outlet water flows also including the blowdown flow. Optionally, the process may include determining the first feedwater flow reduction amount as the difference between the feedwater flow and the outlet water flow. The outlet water flow includes the steam flow and the blowdown flow.

[0103] In this embodiment, in order to maintain the water level of the steam generator at a stable state, the water flow rate entering the steam generator and the water flow rate leaving the steam generator should be the same, that is, the above-mentioned water flow rate should be the same as the sum of the above-mentioned steam flow rate and the above-mentioned sewage flow rate. Among them, the above-mentioned steam flow rate and the above-mentioned sewage flow rate can be used as the water flow rate. In the case that the main water supply valve of the steam generator has an upward drift fault, the difference between the above-mentioned water supply flow rate and the above-mentioned water flow rate can be determined as the first water supply flow rate reduction. For example, as shown in formula (4):

[0104] ΔQ FW1 =Q FW -(Q ST +Q PW ) (4)

[0105] Where ΔQ FW1 is the first water flow reduction, Q FW is the water flow rate, Q ST is the steam flow rate, Q PW is the sewage flow rate.

[0106] In this embodiment, when calculating the feed water flow adjustment amount of the above-mentioned steam generator, the influence of the steam flow and the sewage flow on the water output of the steam generator is fully considered, thereby further improving the accuracy of the above-mentioned feed water flow adjustment amount, and further improving the water level control effect of the steam generator.

[0107] For the steam generator, there are multiple target parameters for reflecting the water level status of the steam generator, such as the feed water flow, the current water level value of the steam generator, the preset water level constant, the secondary circuit mirror load, the main feed water valve opening, etc. Therefore, the target parameters for reflecting the water level status of the steam generator can be used to detect whether the steam generator has an upward drift fault.

[0108] Based on this, in an exemplary embodiment, as Figure 9 As shown, the method for detecting the floating fault of the main feedwater valve of the steam generator may include the following steps:

[0109] S901: Obtain one or more sets of target parameters of the steam generator, and detect whether each set of target parameters meets its corresponding detection conditions.

[0110] The target parameter is a parameter used to reflect the water level state of the steam generator.

[0111] In this embodiment, one or more groups of parameters reflecting the water level status of the steam generator can be obtained, and then, for each group of target parameters, it can be detected whether the group of target parameters meets its corresponding detection conditions, and the above detection conditions are used to detect whether the main water supply valve of the steam generator has an upward drift fault.

[0112] S902: If the number of target parameter groups that meet the corresponding detection conditions is not less than a preset value, it is determined that an upward drift fault is detected in the main feedwater valve of the steam generator.

[0113] Furthermore, after obtaining a test result indicating whether each set of target parameters satisfies its corresponding test condition, the number of target parameter sets that satisfy the corresponding test condition can be determined. Furthermore, if the number of target parameter sets that satisfy the corresponding test condition is not less than a preset value, then at least the preset number of target parameter sets that indicate a drift-up fault in the main feedwater valve of the steam generator can be determined, thereby confirming that a drift-up fault in the main feedwater valve of the steam generator has been detected. Undoubtedly, the preset value is not less than 1 and not greater than the total number of target parameter sets obtained.

[0114] Optionally, the number of groups of target parameters obtained is 1, and the above-mentioned preset value is 1. Then, if the obtained target parameters meet their corresponding detection conditions, it can be directly determined that an upward drift fault has been detected in the main feed water valve of the steam generator.

[0115] Optionally, when there are multiple groups of target parameters obtained and the above-mentioned preset value is 1, as long as there is at least one group of target parameters among the multiple groups of target parameters obtained that meets its corresponding detection conditions, it can be directly determined that an upward drift fault has been detected in the main feed water valve of the steam generator.

[0116] In the above two optional specific embodiments, the detection process of the floating fault of the main feed water valve of the steam generator can be simplified, the detection efficiency of the floating fault of the main feed water valve of the steam generator can be improved, and then the water level control efficiency of the steam generator can be improved.

[0117] Optionally, the number of groups of target parameters obtained is multiple, and the above-mentioned preset value is greater than 1 and less than the total number of groups of target parameters obtained. Then, only when more than two groups of target parameters meet their corresponding detection conditions can it be determined that the main feed water valve of the steam generator has an upward drift fault.

[0118] Optionally, the number of groups of target parameters obtained is multiple, and the above-mentioned preset value is the total number of groups of target parameters obtained. Then, only when the multiple groups of target parameters obtained meet their corresponding detection conditions can it be determined that the main feed water valve of the steam generator has an upward drift fault.

[0119] Among them, in the above two optional specific implementation methods, multiple confirmations are used to determine that the main feed water valve of the steam generator has an upward drift fault, thereby effectively eliminating the impact of changes in the state of the nuclear power unit, such as the transient state, load increase or load decrease of the nuclear power unit, etc., improving the detection accuracy of the upward drift fault of the main feed water valve and improving the water level control effect of the steam generator.

[0120] In this embodiment, a method for detecting the main feed water valve floating fault is provided. The main feed water valve floating fault is detected using target parameters that reflect the water level state of the steam generator. This can effectively detect the main feed water valve floating fault and improve the water level control effect of the steam generator.

[0121] In an exemplary embodiment, in S901 above, obtaining one or more sets of target parameters of the steam generator and detecting whether each set of target parameters meets its corresponding detection condition includes at least one of the following:

[0122] 1) Obtain the steam flow of the steam generator and the feed water flow detected by multiple flow detection devices installed on the steam generator as a set of target parameters, and detect whether the flow difference between each feed water flow and steam flow is greater than a first threshold; if so, determine that the target parameter meets its corresponding detection condition.

[0123] In order to more accurately detect the feedwater flow of the steam generator, a flow detector is usually redundantly installed on the steam generator. Therefore, the steam flow of the steam generator and the feedwater flow detected by multiple flow detection devices installed on the steam generator can be obtained. The above steam flow and multiple feedwater flow rates are used as a set of target parameters. By detecting whether the feedwater flow is higher than the steam flow, it is possible to detect whether the main feedwater valve of the steam generator has an over-drift fault. Among them, it can be detected whether the flow difference between each feedwater flow and steam flow obtained above is greater than a first threshold. If so, it is determined that the set of target parameters meets the corresponding detection conditions. That is, for this set of target parameters, the corresponding detection condition is that the flow difference between each feedwater flow and steam flow is greater than the first threshold. In this way, if the set of target parameters meets the corresponding detection conditions, it can be indicated that the feedwater flow is actually higher than the steam flow, which can indicate that the main feedwater valve of the steam generator has an over-drift fault.

[0124] 2) Obtaining the main feedwater valve opening signal and the required opening signal of the main feedwater valve corresponding to the secondary circuit mirror load of the steam generator as a set of target parameters, and detecting whether the opening difference between the main feedwater valve opening and the required opening is greater than a second threshold; if greater, determining that the target parameter meets its corresponding detection condition.

[0125] To meet the operational needs of the steam generator, the actual opening of the steam generator's main feedwater valve must correspond to the steam generator's secondary circuit mirror load. The actual opening is the main feedwater valve opening signal corresponding to the steam generator's secondary circuit mirror load. To ensure the normal operation of the nuclear power unit and maintain the steam generator's water level at a stable state, the main feedwater valve has an expected opening signal, namely, a required opening signal for the main feedwater valve. Therefore, the main feedwater valve opening signal corresponding to the steam generator's secondary circuit mirror load and the required opening signal for the main feedwater valve can be obtained and used as a set of target parameters. By detecting whether the main feedwater valve opening signal corresponding to the secondary circuit mirror load is excessively large compared to the required opening signal for the main feedwater valve, the presence of an over-drift fault in the steam generator's main feedwater valve can be detected. The difference between the main feedwater valve opening signal corresponding to the secondary circuit mirror load and the required opening signal for the main feedwater valve can be detected to determine whether it exceeds a second threshold. If so, the set of target parameters is determined to meet its corresponding detection conditions. That is, for this set of target parameters, the corresponding detection condition is that the difference between the main feedwater valve opening signal corresponding to the secondary circuit mirror load and the main feedwater valve's required opening signal is greater than a second threshold. Thus, if this set of target parameters meets its corresponding detection condition, it can be indicated that the expected and actual openings of the main feedwater valve are inconsistent, and that the actual opening of the main feedwater valve is larger than the required opening signal of the main feedwater valve, indicating that the main feedwater valve of the steam generator has an over-drift fault.

[0126] 3) Obtain the current water level value and the preset water level setting value of the steam generator as a set of target parameters, and detect whether the height difference between the current water level value and the water level setting value is greater than a third threshold; if greater, determine that the target parameter meets its corresponding detection condition.

[0127] During normal use of a steam generator, the water level of the steam generator is maintained in a stable state, that is, its water level value is maintained at a preset water level value. Therefore, the current water level value and the preset water level value of the steam generator can be obtained and used as a set of target parameters. By detecting whether the current water level value is higher than the preset water level value, it is possible to detect whether the main feedwater valve of the steam generator has an upward drift fault. Specifically, it is possible to detect whether the height difference between the current water level value and the preset water level value is greater than a third threshold. If so, it is determined that the set of target parameters meets its corresponding detection conditions. That is, for this set of target parameters, its corresponding detection condition is that the height difference between the current water level value and the preset water level value is greater than the third threshold. Thus, if the set of target parameters meets its corresponding detection conditions, it can be determined that the current water level value is indeed higher than the preset water level value, indicating that the main feedwater valve of the steam generator has an upward drift fault.

[0128] Optionally, the method for executing S901 is to execute the above three items 1) to 3). Then, when the result of at least one of the tests is yes, it can be determined that the main feedwater valve of the steam generator has a drift fault; when the results of at least two of the tests are yes, it can be determined that the main feedwater valve of the steam generator has a drift fault; and when the results of all three of the tests are yes, it can be determined that the main feedwater valve of the steam generator has a drift fault.

[0129] In summary, the water level control method for a steam generator provided in the embodiment of the present application can be understood as a method for automatically controlling a bypass valve in a main feed water valve drift fault mode of a steam generator, which mainly includes two parts: main feed water valve drift judgment and bypass valve automatic control.

[0130] In an exemplary embodiment, Figure 10 As shown in the figure, a logic diagram of a water level control method for a steam generator provided by an embodiment of the present application (a method for automatically controlling a bypass valve in a main feedwater valve drift fault mode of a steam generator) mainly includes two parts: main feedwater valve drift judgment (main feedwater valve drift fault judgment) and bypass valve automatic control. The bypass valve automatic control part includes two parts: manual switching of the bypass valve and setting the bypass valve opening.

[0131] If the main water supply valve is judged to have an over-floating fault, the water supply pump or bypass valve will be automatically controlled. The selection of automatic water supply pump control or bypass valve control is based on the deviation of the water supply flow (the amount of accumulated water flow adjustment) through logical judgment.

[0132] If the deviation of the feed water flow (feed water flow adjustment) exceeds the change in feed water flow caused by the bypass valve switching from a fully open state to a fully closed state, the feed water pump automatic control is selected, otherwise the bypass valve automatic control is selected. When the main feed water valve determines that there is an upward drift fault, and the deviation of the feed water flow (feed water flow adjustment) is within the adjustable range of the bypass valve, that is, the deviation of the feed water flow (feed water flow adjustment) does not exceed the above-mentioned feed water flow variable, the bypass valve is placed in manual mode and the bypass valve opening is set at the same time. When the water level returns to normal, the bypass valve is reset to automatic mode. Among them, the manual mode of the bypass valve refers to the bypass valve adjusting its opening according to the bypass valve opening signal transmitted from the outside, and the automatic mode refers to the bypass valve automatically adjusting its opening according to the use status of the steam generator.

[0133] In this embodiment, if Figure 11 As shown in the figure, the logic diagram of the main feedwater valve drift judgment, in which the steam generator water level L SG , Secondary circuit load P PW , Main water supply valve opening signal VO1 , Steam generator water level set value L SP , water flow Q FW , steam flow Q ST Participate in the judgment of the main water supply valve floating.

[0134] Among them, Figure 12 As shown, two flow detection devices are provided for the redundancy of the steam generator, which can realize the redundant detection of the feed water flow of the steam generator and obtain the two detected feed water flow rates Q FW1 and Q FW2 , the above Q FW1 and Q FW2 Respectively with steam flow Q 2T For comparison, if Q FW1 -Q ST >C1、Q FW2 -Q ST >C1, where C1 is the preset first threshold, it means that the feed water flow of the steam generator is actually too high.

[0135] Secondary circuit load P PW The corresponding main water supply valve opening signal f(P PW ) and the required opening signal V of the main water supply valve O1 is greater than the preset second threshold C2, that is, f(P PW )-V O1 >C2, it means that there is a discrepancy between the actual opening signal of the main water supply valve and the expected opening signal.

[0136] Steam generator current water level L SG The preset water level value L of the steam generator SP Compare, if L SG -L SP >C3, where C3 is the preset third threshold, indicating that the current water level of the steam generator is actually too high.

[0137] If all three of the above conditions are met, the presence of a main feedwater valve drift fault is confirmed. If the other two steam generators sharing the same feedwater pump as the main feedwater valve drift fault do not experience this main feedwater valve drift fault, the impact of unit transients, unit load increases or decreases, and other state changes on the water level of the steam generator with the main feedwater valve drift fault can be effectively eliminated, effectively confirming the main feedwater valve drift fault.

[0138] The bypass valve opening setting in the bypass valve automatic control includes two steps: determining the opening signal and adjusting the opening of the bypass valve. Figure 12 The following is the logic diagram of bypass valve opening setting, where the water flow rate Q FW , steam flow QST , sewage flow Q PW , steam-water pressure difference ΔP SW , steam generator water level L SG , Steam generator water level set value L SP , water temperature T FW The bypass valve opening characteristic (the correspondence between the preset feed water flow and the opening signal of the bypass valve of the steam generator) is combined to participate in the bypass valve opening setting calculation (determine the bypass valve opening signal).

[0139] Among them, the water flow rate Q FW , steam flow Q ST , sewage flow Q PW Participate in the calculation of the mass deviation of water in the steam generator. If the water level in the steam generator is expected to remain constant, then according to the law of conservation of mass, the amount of water entering the steam generator, Q FW The amount of water discharged from the steam generator Q ST +Q PW Equal, that is, Q FW =Q ST +Q PW However, when the main feedwater valve has an upward drift fault, the water volume Q FW Greater than the water output Q of the steam generator ST +Q PW To prevent the water level in the steam generator from rising continuously, it is necessary to reduce the feed water flow rate (feed water flow adjustment amount) Q FW .

[0140] Among them, Q FW Including the first water flow reduction ΔQ FW1 and the second feedwater flow reduction ΔQ FW2 , then use the above formula (3) to calculate the water flow adjustment amount Q FW .

[0141] ΔQ FW =ΔQ FW1 +ΔQ FW2 (3)

[0142] Where ΔQ FW1 The calculation process can be called steam generator quality deviation calculation, ΔQ FW2 The calculation process can be called steam generator feed water demand calculation.

[0143] Specifically, using the above formula (4), calculate the first water flow reduction ΔQ FW1 .

[0144] ΔQ FW1 =Q FW -(Q ST +QPW ) (4)

[0145] Using the above formula (1) and formula (2), calculate the second water flow reduction ΔQ FW2 Specifically, the current water level value of the steam generator is L SG The preset water level value L of the steam generator SP Compare and calculate the height difference L SG -L SP , and use the above formula (1) to calculate the additional feed water volume in the steam generator through the steam generator volume:

[0146] V d =πr 2 (L SG -L SP ) (1)

[0147] Then, using the above formula (2), the volume flow of the water supply volume is converted into the water supply flow with mass as the dimension, and the second water supply flow reduction is obtained. In the conversion process, the correction coefficient K1 of the water supply temperature to the volume is mainly considered, and the corresponding relationship between the water supply temperature and the correction coefficient is as follows: Figure 8 As shown. Among them,

[0148] ΔQ FW2 =V d / (K1T1) (2)

[0149] Finally, the steam-water pressure difference ΔP during normal operation of the steam generator SW Maintain unchanged, that is, the pressure difference before and after the bypass valve remains constant, according to Figure 3 The bypass valve opening characteristic curve of the steam generator shown in FIG, that is, the corresponding relationship between the preset feed water flow and the bypass valve opening signal of the steam generator, and the bypass valve opening signal V is obtained. O2 .

[0150] Based on the above embodiment, this embodiment provides a preferred implementation method for realizing water level control of the steam generator. Figure 13 As shown, the preferred embodiment includes the following steps:

[0151] S1301, obtaining the steam flow of the steam generator and the feed water flow detected by multiple flow detection devices installed on the steam generator, and detecting whether the flow difference between each feed water flow and steam flow is greater than a first threshold.

[0152] S1302, obtaining a main feedwater valve opening signal and a required opening signal of the main feedwater valve corresponding to the secondary circuit mirror load of the steam generator, and detecting whether the opening difference between the main feedwater valve opening and the required opening is greater than a second threshold.

[0153] S1303, obtaining the current water level value and the preset water level value of the steam generator, and detecting whether the height difference between the current water level value and the preset water level value is greater than a third threshold.

[0154] S1304: If the detection results of the above steps S1301-S1303 are all yes, it is determined that an upward drift fault is detected in the main feed water valve of the steam generator.

[0155] S1305: Determine the flow difference between the water supply flow and the water outlet flow as the first water supply flow reduction.

[0156] S1306, determine the height difference between the current water level value of the steam generator and the preset water level value, and determine the second feed water flow reduction based on the height difference, the shape of the steam generator, the correction coefficient of the water temperature to the volume of the steam generator and the steam generator water level adjustment time.

[0157] S1307: Determine the sum of the first feedwater flow reduction amount and the second feedwater flow reduction amount as the feedwater flow adjustment amount of the steam generator.

[0158] S1308: When the feedwater flow adjustment amount does not exceed the preset adjustment amount, determine the target difference between the feedwater flow of the steam generator when the bypass valve is in the fully open state and the feedwater flow adjustment amount.

[0159] S1309 , determining the bypass valve opening signal corresponding to the target difference in the bypass valve opening characteristic curve of the steam generator, and adjusting the bypass valve opening according to the opening signal to achieve water level control of the steam generator.

[0160] It should be understood that, although the various steps in the flowcharts involved in the various embodiments described above are displayed in sequence according to the instructions of the arrows, these steps are not necessarily executed in sequence in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order restriction on the execution of these steps, and these steps can be executed in other orders. Moreover, at least a portion of the steps in the flowcharts involved in the various embodiments described above can include multiple steps or multiple stages, and these steps or stages are not necessarily executed and completed at the same time, but can be executed at different times, and the execution order of these steps or stages is not necessarily to be carried out in sequence, but can be executed in turn or alternately with other steps or at least a portion of steps or stages in other steps.

[0161] Based on the same inventive concept, embodiments of the present application further provide a steam generator water level control device for implementing the aforementioned steam generator water level control method. The solution provided by this device is similar to the solution described in the aforementioned method. Therefore, the specific limitations of one or more steam generator water level control device embodiments provided below can be found in the aforementioned limitations of the steam generator water level control method and will not be further elaborated here.

[0162] In an exemplary embodiment, Figure 14 As shown, a water level control device for a steam generator is provided, comprising: a flow determination module 1410, a signal determination module 1420 and a valve adjustment module 1430, wherein:

[0163] The flow determination module 1410 is configured to determine the feedwater flow adjustment amount of the steam generator based on the inlet and outlet water flows, the current water level, and a preset water level value when a drift fault is detected in the main feedwater valve of the steam generator;

[0164] a signal determination module 1420 for determining an opening signal of the bypass valve based on a correspondence between a preset feedwater flow rate and an opening signal of the bypass valve of the steam generator, and a feedwater flow rate adjustment amount;

[0165] The valve adjustment module 1430 is used to adjust the opening of the bypass valve according to the opening signal to achieve water level control of the steam generator.

[0166] In an exemplary embodiment, the inlet and outlet water flows include at least feed water flow and steam flow; the flow determination module 1410 includes:

[0167] a first determining submodule, configured to determine a first feedwater flow reduction amount based on a flow difference between the feedwater flow and the steam flow;

[0168] The difference determination submodule is used to determine the height difference between the current water level value of the steam generator and the preset water level value;

[0169] a second determining submodule, configured to determine a second feedwater flow reduction amount based on the height difference and the shape of the steam generator;

[0170] The flow determination submodule is configured to determine the sum of the first feedwater flow reduction amount and the second feedwater flow reduction amount as the feedwater flow adjustment amount of the steam generator.

[0171] In an exemplary embodiment, the inlet and outlet water flows also include sewage flow; the first determination submodule is specifically used to: determine the flow difference between the feed water flow and the outlet water flow as the first feed water flow reduction; wherein the outlet water flow includes steam flow and sewage flow.

[0172] In an exemplary embodiment, the flow determination module 1410 includes:

[0173] a judgment submodule, configured to obtain one or more sets of target parameters for the steam generator and detect whether each set of target parameters satisfies its corresponding detection conditions; wherein the target parameters are parameters used to reflect the water level status of the steam generator, and if the number of sets of target parameters that satisfy their corresponding detection conditions is not less than a preset value, then a third determination submodule is triggered;

[0174] The third determining submodule is configured to determine whether an upper drift fault is detected in the main feedwater valve of the steam generator.

[0175] In an exemplary embodiment, the determination submodule is configured to perform at least one of the following:

[0176] Obtaining the steam flow rate of the steam generator and the feed water flow rate detected by multiple flow detection devices installed on the steam generator as a set of target parameters, and detecting whether the flow difference between each feed water flow rate and the steam flow rate is greater than a first threshold; if so, determining that the target parameter meets the corresponding detection condition;

[0177] Obtaining a main feedwater valve opening signal and a required opening signal of the main feedwater valve corresponding to the secondary circuit mirror load of the steam generator as a set of target parameters, and detecting whether the opening difference between the main feedwater valve opening and the required opening is greater than a second threshold; if so, determining that the target parameter satisfies its corresponding detection condition;

[0178] The current water level value and water level set value of the steam generator are obtained as a set of target parameters, and it is detected whether the height difference between the current water level value and the preset water level set value is greater than a third threshold; if it is greater, it is determined that the target parameter meets its corresponding detection condition.

[0179] In an exemplary embodiment, the signal determination module 1420 is specifically used to: determine the opening signal of the bypass valve based on the correspondence between the preset feed water flow and the opening of the bypass valve of the steam generator, and the feed water flow adjustment amount, when the feed water flow adjustment amount does not exceed the preset adjustment amount; wherein the preset adjustment amount is used to characterize the change in feed water flow caused by the bypass valve switching from a fully open state to a fully closed state.

[0180] In an exemplary embodiment, the water level control device for a steam generator further includes:

[0181] The judgment module is used to judge whether the water level value of the steam generator is restored to the water level setting value every preset time period; if not, return to the trigger flow determination module 1410 until the water level value of the steam generator is restored to the water level setting value.

[0182] In an exemplary embodiment, the signal determination module 1420 is specifically configured to:

[0183] Determine the target difference between the feedwater flow rate of the steam generator and the feedwater flow rate adjustment when the bypass valve is in the fully open state;

[0184] In the correspondence between the preset feedwater flow rate and the opening signal of the bypass valve of the steam generator, the opening signal of the bypass valve corresponding to the target difference is determined.

[0185] Each module in the steam generator water level control device can be implemented in whole or in part through software, hardware, or a combination thereof. Each module can be embedded in or independent of a processor in a computer device in the form of hardware, or can be stored in a memory in the computer device in the form of software, so that the processor can call and execute the corresponding operations of each module.

[0186] In an exemplary embodiment, a computer device is provided, the internal structure of which can be as follows: Figure 15 As shown. The computer device includes a processor, a memory, an input / output interface (Input / Output, abbreviated as I / O) and a communication interface. The processor, memory and input / output interface are connected via a system bus, and the communication interface is connected to the system bus via the input / output interface. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for the operation of the operating system and computer program in the non-volatile storage medium. The database of the computer device is used to store data such as the inlet and outlet water flow of the steam generator, the current water level value, the budgeted water level setting value, the preset correspondence between the feed water flow and the opening signal of the bypass valve of the steam generator. The input / output interface of the computer device is used to exchange information between the processor and an external device. The communication interface of the computer device is used to communicate with an external terminal via a network connection. When the computer program is executed by the processor, a water level control method for a steam generator is implemented.

[0187] In one embodiment, a computer device is further provided, including a memory and a processor. The memory stores a computer program, and the processor implements the steps in the above method embodiments when executing the computer program.

[0188] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the steps in the above-mentioned method embodiments are implemented.

[0189] In one embodiment, a computer program product is provided, including a computer program, which implements the steps in the above method embodiments when executed by a processor.

[0190] Those skilled in the art will appreciate that all or part of the processes in the above-mentioned embodiment methods can be implemented by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, database or other media used in the embodiments provided in this application may include at least one of non-volatile memory and volatile memory. Non-volatile memory may include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory may include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM). The database involved in the various embodiments provided herein may include at least one of a relational database and a non-relational database. Non-relational databases may include, but are not limited to, distributed databases based on blockchains. The processor involved in the various embodiments provided herein may be, but are not limited to, a general-purpose processor, a central processing unit (CPU), a graphics processing unit (GPU), a digital signal processor (DSP), a programmable logic unit (PLC), a data processing logic unit based on quantum computing, an artificial intelligence (AI) processor, and the like.

[0191] The technical features of the above embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this application.

[0192] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present application. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, and these modifications and improvements fall within the scope of protection of the present application. Therefore, the scope of protection of the present application shall be determined by the appended claims.

Claims

1. A water level control method for a steam generator, characterized in that: The method comprises: When a main feedwater valve of a steam generator is detected to have an upward drift fault, the feedwater flow adjustment amount of the steam generator is determined according to the inlet and outlet water flow of the steam generator, the current water level value and the preset water level value; Determining the opening signal of the bypass valve based on a correspondence between a preset feedwater flow rate and an opening signal of the bypass valve of the steam generator, and the feedwater flow rate adjustment amount; The opening of the bypass valve is adjusted according to the opening signal to achieve water level control of the steam generator.

2. The method according to claim 1, characterized in that The inlet and outlet water flows include at least a feed water flow and a steam flow; and determining the feed water flow adjustment amount of the steam generator according to the inlet and outlet water flows, the current water level value, and a preset water level value of the steam generator includes: determining a first feedwater flow reduction amount based on a flow difference between the feedwater flow and the steam flow; Determine the height difference between the current water level value of the steam generator and a preset water level value; determining a second feedwater flow reduction amount based on the height difference and the shape of the steam generator; The sum of the first feedwater flow reduction amount and the second feedwater flow reduction amount is determined as the feedwater flow adjustment amount of the steam generator.

3. The method according to claim 2, characterized in that The inlet and outlet water flows also include a sewage flow; and determining a first feedwater flow reduction amount based on a flow difference between the feedwater flow and the steam flow includes: The flow difference between the feed water flow and the outlet water flow is determined as a first feed water flow reduction; wherein the outlet water flow includes the steam flow and the sewage flow.

4. The method according to claim 1, wherein The detecting that a main feedwater valve of the steam generator has an upward drift fault includes: Obtaining one or more sets of target parameters of the steam generator, and detecting whether each set of target parameters satisfies its corresponding detection condition; wherein the target parameters are parameters used to reflect the water level state of the steam generator; If the number of target parameter groups that meet the corresponding detection conditions is not less than a preset value, it is determined that an upward drift fault is detected in the main feed water valve of the steam generator.

5. The method according to claim 4, characterized in that The obtaining of one or more sets of target parameters of the steam generator and detecting whether each set of target parameters satisfies its corresponding detection condition includes at least one of the following: obtaining a steam flow rate of the steam generator and a feed water flow rate detected by a plurality of flow detection devices installed on the steam generator as a set of target parameters, and detecting whether a flow difference between each feed water flow rate and the steam flow rate is greater than a first threshold; If so, it is determined that the target parameter meets its corresponding detection condition; obtaining a main feedwater valve opening signal and a required opening signal of the main feedwater valve corresponding to the secondary circuit mirror load of the steam generator as a set of target parameters, and detecting whether an opening difference between the main feedwater valve opening and the required opening is greater than a second threshold; if so, determining that the target parameter satisfies its corresponding detection condition; The current water level value and the water level set value of the steam generator are obtained as a set of target parameters, and it is detected whether the height difference between the current water level value and the water level set value is greater than a third threshold; if it is greater, it is determined that the target parameter meets its corresponding detection condition.

6. The method according to any one of claims 1 to 5, characterized in that The determining of the bypass valve opening signal based on the correspondence between the preset feedwater flow rate and the opening of the bypass valve of the steam generator, and the feedwater flow rate adjustment amount, includes: When the feedwater flow adjustment amount does not exceed a preset adjustment amount, determining an opening signal of the bypass valve based on a correspondence between a preset feedwater flow rate and an opening of the bypass valve of the steam generator and the feedwater flow adjustment amount; The preset adjustment amount is used to represent the change in water flow caused by the bypass valve being switched from a fully open state to a fully closed state.

7. The method according to any one of claims 1 to 5, characterized in that After adjusting the opening of the bypass valve according to the opening signal, the method further includes: At predetermined intervals, determining whether the water level of the steam generator has returned to the set water level; If not, return to the step of determining the feed water flow adjustment amount of the steam generator based on the inlet and outlet water flow of the steam generator, the current water level value and the preset water level constant, until the water level value of the steam generator is restored to the water level constant.

8. The method according to any one of claims 1 to 5, characterized in that The determining the opening signal of the bypass valve based on the correspondence between the preset feedwater flow rate and the opening signal of the bypass valve of the steam generator, and the feedwater flow rate adjustment amount, includes: determining a target difference between the feedwater flow rate of the steam generator and the feedwater flow rate adjustment amount when the bypass valve is in a fully open state; In the correspondence between the preset feed water flow rate and the opening signal of the bypass valve of the steam generator, the opening signal of the bypass valve corresponding to the target difference is determined.

9. A water level control device for a steam generator, characterized in that: The device comprises: a flow determination module, configured to determine a feedwater flow adjustment amount of the steam generator based on the inlet and outlet water flows, the current water level value, and a preset water level value of the steam generator when a drift fault is detected in the main feedwater valve of the steam generator; a signal determination module, configured to determine the opening signal of the bypass valve based on a correspondence between a preset feedwater flow rate and an opening signal of the bypass valve of the steam generator, and the feedwater flow rate adjustment amount; The valve adjustment module is used to adjust the opening of the bypass valve according to the opening signal to achieve water level control of the steam generator.

10. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 8 are implemented.

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